Eastern Box Turtles Research Articles

Delineating modern variation from extinct morphology in the fossil record using shells of the Eastern Box Turtle (Terrapene carolina).

Characterization of morphological variation in the shells of extant Eastern Box Turtles, Terrapene carolina, provides a baseline for comparison to fossil populations. It also provides an example of the difficulties inherent to recognizing intraspecific diversity in the fossil record. The degree to which variation in fossils of T. carolina can be accommodated by extant variation in the species has been disagreed upon for over eighty years. Using morphometric analyses of the carapace, I address the relationship between modern and fossil T. carolina in terms of sexual dimorphism, geographic and subspecific variation, and allometric variation. Modern T. carolina display weak male-biased sexual size dimorphism. Sexual shape dimorphism cannot be reliably detected in the fossil record. Rather than a four-part subspecific division, patterns of geographic variation are more consistent with clinal variation between various regions in the species distribution. Allometric patterns are qualitatively similar to those documented in other emydid turtles and explain a significant amount of shape variation. When allometric patterns are accounted for, Holocene specimens are not significantly different from modern specimens. In contrast, several geologically older specimens have significantly different carapace shape with no modern analogue. Those large, fossilized specimens represent extinct variation occupying novel portions of morphospace. This study highlights the need for additional documentation of modern osteological variation that can be used to test hypotheses of intraspecific evolution in the fossil record.

An open-source hardware GPS data logger for wildlife radio-telemetry studies: A case study using Eastern box turtles

Abstract Global Positioning System (GPS) telemetry technology has been a boon to animal spatial ecology studies. Oftentimes, the main limitation to widespread application of this technology is the cost, which can dictate the number of individuals outfitted with GPS technology, thereby limiting sample sizes. Here, we discuss the development of a low-cost, customizable, open-source hardware GPS logger for use in animal movement studies. We also present results from field tests with Eastern box turtles (Terrapene carolina) in northwestern Ohio. These GPS loggers have the potential to augment existing projects and facilitate studies that would be otherwise cost-prohibitive.

Identification of Hemotropic Mycoplasmas in an Eastern Box Turtle ( Terrapene carolina carolina) and a Yellow-bellied Slider ( Trachemys scripta scripta) from North Carolina, USA.

Mycoplasma spp. are known from several chelonian and other reptilian species. We determined if turtles obtained by the Turtle Rescue Team at North Carolina State University are carriers of hemotropic Mycoplasma or Bartonella spp. Spleen samples were collected at necropsy during May through July, 2014 from 53 turtles of seven species. All turtles were dead or were euthanized upon arrival due to severe traumatic injuries, or they died shortly after beginning treatment. We used PCR amplification for both bacterial genera; Bartonella spp. DNA was not amplified. Based upon sequencing of the 16S rRNA subunit, one eastern box turtle ( Terrapene carolina carolina) and one yellow-bellied slider ( Trachemys scripta scripta) were infected with Mycoplasma spp. that have genetic similarities to strains that infect other animals.

Effects of gap-based silviculture on thermal biology of a terrestrial reptile

Context Terrestrial reptiles require varied thermal environments to promote optimal physiological performance, growth, reproduction, and survival. Aims Our study was designed to determine whether gap-based silvicultural practices offer suitable thermal environments for eastern box turtles (Terrapene carolina) by examining environmental temperature variation and body temperature of eastern box turtles in, and adjacent to, canopy gaps. Methods We recorded box turtle body temperature from 20 radio-tracked turtles and environmental temperatures (canopy gaps and undisturbed habitat) using temperature loggers from June to September 2014 in a managed forest after canopy gaps (0.28–1.13 ha gap–1) were created via gap-based silviculture. Key results Over the four-month study period, gap temperatures were generally higher than adjacent undisturbed microhabitats. Box turtle body temperatures were closely correlated with environmental temperatures in undisturbed habitat in June and July. Turtle body temperatures were, however, closely correlated with environmental temperatures in canopy gaps in August and September. In addition, box turtles in our study had activity areas that overlapped canopy gaps from 0 to 65%, depending on the individual. As percentage overlap of canopy gaps increased, turtle body temperatures were increasingly correlated with canopy gap temperatures. Furthermore, as percentage overlap of canopy gaps increased, daily mean body temperature records consistently stayed within the preferred box turtle body temperature range (20.2–26.2°C). Conclusions Our study suggests that gap-based silviculture can create thermally compatible environments for box turtles depending on the time of day and year, and that box turtles use these microhabitats to thermoregulate. Implications The application of relatively small-scale silvicultural practices (≤1 ha gap–1) that provide heterogeneity in forest structure, composition, and function may be a useful alternative to clearcutting and other intensive harvesting methods that are associated with declines in terrestrial reptile populations.

Venous blood gas in free-living eastern box turtles (Terrapene carolina carolina) and effects of physiologic, demographic and environmental factors.

Sustainable wildlife populations depend on healthy individuals, and the approach to determine wellness of individuals is multifaceted. Blood gas analysis serves as a useful adjunctive diagnostic test for health assessment, but it is uncommonly applied to terrestrial reptiles. This study established reference intervals for venous blood gas panels in free-living eastern box turtles (Terrapene carolina carolina, N = 102) from Illinois and Tennessee, and modeled the effects of environmental and physiologic parameters on each blood gas analyte. Blood gas panels included pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), total carbon dioxide (TCO2), bicarbonate (HCO3-), base excess (BE) and lactate. Candidate sets of general linear models were constructed for each blood gas analyte and ranked using an information-theoretic approach (AIC). Season, packed cell volume (PCV) and activity level were the most important predictors for all blood gas analytes (P < 0.05). Elevations in PCV were associated with increases in pCO2 and lactate, and decreases in pH, pO2, HCO3-, TCO2 and BE. Turtles with quiet activity levels had lower pH and pO2 and higher pCO2 than bright individuals. pH, HCO3-, TCO2 and BE were lowest in the summer, while pCO2 and lactate were highest. Overall, blood pH was most acidic in quiet turtles with elevated PCVs during summer. Trends in the respiratory and metabolic components of the blood gas panel tended to be synergistic rather than antagonistic, demonstrating that either (1) mixed acid-base disturbances are common or (2) chelonian blood pH can reach extreme values prior to activation of compensatory mechanisms. This study shows that box turtle blood gas analytes depend on several physiologic and environmental parameters and the results serve as a baseline for future evaluation.

Consistently bolder turtles maintain higher body temperatures in the field but may experience greater predation risk

Behavioral ecologists have assumed that animals will optimize behavior to match their current situation, yet studies reveal limited behavioral flexibility and extensive variation among individuals in their response to a similar stimulus. This phenomenon is referred to as “animal personality,” and recent efforts seek to determine the implications of personality for interactions with the biotic and abiotic environment. Doing so promises to illuminate how selection is operating on behavioral traits and, consequently, how stable, among-individual variation in behavioral types is maintained evolutionarily. We examined a natural population of forest-dwelling eastern box turtles (Terrapene carolina) to understand the effects of differences in levels of boldness on thermoregulatory behavior, injury history, and movement rates. Repeated behavioral trials revealed that individual turtles varied consistently and dramatically in boldness (latency to emerge from the shell or begin moving after handling and confinement). Behavioral differences were independent of phenotypic state or environmental conditions, suggesting the existence of personality in these turtles. Moreover, bolder turtles maintained higher body temperatures in the field and tended to have more damage to their shells, possibly indicative of more frequent predation attempts. Little work has been done on personality in terrestrial ectotherms, and this study enhances our understanding of this phenomenon by highlighting the potential trade-off between mortality and thermoregulation. Animals often exhibit markedly different personality traits from each other. We sought to understand how personality traits affect interactions with the environment, and thus how natural selection may be acting upon and maintaining behavioral variation. We studied this in terrestrial ectotherms, box turtles, for whom the trade-off between basking and predation risk may be a significant factor. We found that individual turtles differed consistently in boldness (time spent hiding and immobile after handling) and that bolder turtles maintained higher body temperatures but tended to have more injuries on their shells. This suggests that being bold is beneficial for thermoregulation, which may enhance growth and fecundity, but could expose turtles to greater risk of predation. Variation in the expression of boldness may, therefore, serve to maintain behavioral variation in the population.

Thermoregulatory performance and habitat selection of the eastern box turtle (Terrapene carolina carolina).

Environmental conditions may affect individual physiological processes that influence short-term performance and ultimately growth, survival and reproduction. As such, habitats selected by animals must provide suitable and adequate resources. Ectothermic species are highly dependent on climatic conditions and ambient temperatures that dictate body temperature regulation and in turn physiological processes. We investigated the thermoregulatory performance, habitat selection, and movements of an ectothermic vertebrate, the Eastern box turtle (Terrapene carolina carolina) to assess the importance of thermoregulatory physiology in habitat selection. We evaluated the relationship between habitat selection and thermoregulatory performance in Southwest Ohio over two active seasons from May until October. We found that T. carolina selected shaded habitats, including evergreen and deciduous forests, as well as herbaceous grasslands, conformed to the ambient temperatures throughout the active season, although these habitats had temperatures below those expected based on thermal optima of box turtles. Further, we found that movement was not correlated with internal body temperature. Our study shows that thermal conditions are not paramount in habitat selection of box turtles, but that cooler temperatures do not have an effect on the extent of their locomotion.

DETECTION OF RANAVIRUS USING BONE MARROW HARVESTED FROM MORTALITY EVENTS IN EASTERN BOX TURTLES ( TERRAPENE CAROLINA CAROLINA).

The causes of free-living chelonian mortality events are often unknown because of infrequent recovery of remains and rapid postmortem decomposition. This study describes a technique to harvest bone marrow and detect frog virus 3-like ranavirus (FV3) using quantitative polymerase chain reaction in skeletonized eastern box turtles ( Terrapene carolina carolina) ( N = 87), and assesses agreement with concurrent perimortem samples ( N = 14). FV3 was detected in bone marrow samples from 12 turtle shells (14%). Three of 14 turtles had detectable FV3 loads in both bone marrow and perimortem samples, two turtles had detectable FV3 in bone marrow only, and nine turtles tested FV3 negative in both bone marrow and concurrent perimortem samples. There was substantial agreement between FV3 testing of bone marrow and other tissues ( κ = 0.658). Harvesting bone marrow from shells is easily performed and can serve as a means for biologists and wildlife veterinarians to improve postmortem surveillance for systemically distributed pathogens, including FV3.

DETECTION OF COPATHOGENS IN FREE-RANGING EASTERN BOX TURTLES ( TERRAPENE CAROLINA CAROLINA) IN ILLINOIS AND TENNESSEE.

Conservation efforts are investigating the impact of diseases within a species of interest, including prevalence and transmission and morbidity and mortality rates. However, the majority of these studies focus solely on the characteristics of a single pathogen. Recently, the role of copathogens has been reported to impact disease susceptibility and mortality. To that effect, a survey was conducted including 318 eastern box turtles ( Terrapene carolina carolina) from populations in Illinois and Tennessee in 2014 and 2015. Blood samples and oral swabs were collected for quantitative polymerase chain reaction (qPCR) of 15 different pathogens performed in a multiplex format using Fluidigm array technology. Four pathogens were found with varying qPCR prevalence: ranavirus (FV3; n = 2, 0.6%), Terrapene herpesvirus 1 (TerHV1; n = 129, 40.7%), box turtle Mycoplasma sp. (BT Myco; n = 14, 4.6%), and box turtle adenovirus (BT Adv1; n = 18, 11%). Thirteen pathogens were not identified in any sample, including Mycoplasma agassizii, M. testudineum, Salmonella enteriditis, S. typhmirium, Borrelia burgdorferi, Anaplasma phagocyophilum, tortoise intranuclear coccidia, Ambystoma tigrinum virus, Bohle iridovirus, Epizootic hematopoietic necrosis virus, and testudinid herpesvirus 2. Copathogen occurrence was rare but was observed in eight individuals with TerHV1-BT Myco detection and two animals with TerHV1-Adv1. Significant differences were observed in pathogen detection across season (TerHV1, BT Adv1, BT Myco, and TerHV1-Myco) and year (TerHV1, BT Adv1, and TerHV1-Myco). The results of this survey highlight that a single pathogen model may not adequately explain pathogen dynamics and that conservation efforts need to be aimed at detecting multiple pathogens in order to fully characterize population health.

Influences on Standard Metabolism in Eastern Box Turtles (Terrapene carolina)

Abstract Knowledge of species-specific patterns of energy use is important for understanding the evolution of life histories as well as for determining how species might respond to alterations in environmental conditions. We measured standard metabolic rates (SMRs) in 59 Eastern Box Turtles (mass range = 106−510 g) and determined how differences in body mass and body temperature (20°C vs. 30°C) influenced SMRs. Rates of standard metabolism were significantly influenced by body mass at body temperatures of 20°C and 30°C and SMR was significantly higher at 30°C (Q10 = 3.04). There was significant among-individual variation in SMR and individuals with higher metabolism at 20°C also tended to have higher metabolism at 30°C.

Diagnosis and treatment of a multidrug-resistant Escherichia coli in a wild eastern box turtle (Terrapene carolina carolina)

An adult male eastern box turtle presented to the Turtle Rescue Team at North Carolina State University with clinical signs of an upper respiratory tract infection. After unsuccessful treatment with...

Thermal biology of eastern box turtles in a longleaf pine system managed with prescribed fire

Fire can influence the microclimate of forest habitats by removing understory vegetation and surface debris. Temperature is often higher in recently burned forests owing to increased light penetration through the open understory. Because physiological processes are sensitive to temperature in ectotherms, we expected fire-maintained forests to improve the suitability of the thermal environment for turtles, and for turtles to seasonally associate with the most thermally-optimal habitats. Using a laboratory thermal gradient, we determined the thermal preference range (Tset) of eastern box turtles, Terrapene carolina, to be 27–31°C. Physical models simulating the body temperatures experienced by turtles in the field revealed that surface environments in a fire-maintained longleaf pine forest were 3°C warmer than adjacent unburned mixed hardwood/pine forests, but the fire-maintained forest was never of superior thermal quality owing to wider Te fluctuations above Tset and exposure to extreme and potentially lethal temperatures. Radiotracked turtles using fire-managed longleaf pine forests maintained shell temperatures (Ts) approximately 2°C above those at a nearby unburned forest, but we observed only moderate seasonal changes in habitat use which were inconsistent with thermoregulatory behavior. We conclude that turtles were not responding strongly to the thermal heterogeneity generated by fire in our system, and that other aspects of the environment are likely more important in shaping habitat associations.

MORBIDITY AND MORTALITY OF WILD TURTLES AT A NORTH CAROLINA WILDLIFE CLINIC: A 10-YEAR RETROSPECTIVE.

The medical records from 1,847 wild turtle patients seen between 2005 and 2014 by the Turtle Rescue Team at the North Carolina State University College of Veterinary Medicine were analyzed. Eastern box turtles (Terrapene carolina carolina; n = 947), yellow-bellied sliders (Trachemys scripta scripta; n = 301), cooters ( Pseudemys spp.; n = 235), common snapping turtles (Chelydra serpentina; n = 165), and eastern painted turtles (Chrysemys picta; n = 93) made up 94.3% of all patients. Patient admissions peaked in May when 25.6% (473/1,847) of all turtles were admitted. Cooters were the most-likely species to be gravid, and the loss of gravid females may put this population at increased risk for decline. The majority of wild turtles presented for anthropogenic causes, primarily vehicular trauma (63.2%; 1,168/1,847), which also had the greatest mortality at 57.8% (675/1,168) of any presenting complaint. Coelomic breach was the presenting injury with greatest risk of dying, increasing the risk of dying by 4.8 times. Other factors that were associated with increased mortality included head injuries, myiasis, and cranial or caudal midline injuries. Of all turtle species, eastern box turtles most commonly presented for nontraumatic conditions including aural abscesses (8.2%; 78/947), upper respiratory infections (6.3%; 60/947), and both conditions concurrently (2.5%; 14/947). While many turtles presented with little to no chance for survival in the wild, 47.6% were eventually released and that number increased to 62.0% released for those that survived 24 hr or longer after presentation. This study adds to the knowledge about the treatment of injured and diseased wild turtles in order to potentially ameliorate the overall impact of humans, especially as a result of vehicular trauma.

CHARACTERIZING THE 25-HYDROXYVITAMIN D STATUS OF TWO POPULATIONS OF FREE-RANGING EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA).

Ultraviolet B radiation is recommended for captive reptiles to stimulate production of adequate levels of vitamin D; however, little is known regarding the vitamin D status in many free-ranging populations. Current reference ranges for vitamin D in eastern box turtles have not yet been established. Sixty free-ranging eastern box turtles (Terrapene carolina carolina) from two well-studied populations in Illinois (n = 24) and Tennessee (n = 36) were assayed for plasma vitamin D concentration in 2014. There were no significant differences in concentrations between individuals in Illinois (mean: 117.5 nM/L) and Tennessee (mean: 98.7 nM/L) (P = 0.129) populations. Similarly, there were no differences in concentrations based on age class (P = 0.533) or sex (P = 0.532). There was a significant correlation between UV at the time of capture and vitamin D concentrations (R = 0.301, P = 0.030). Vitamin D was not correlated with total calcium (R = 0.018, P = 0.89) or Ca : P ratio (R = 0.025, P = 0.85). Diseases in captive individuals, including secondary nutritional hyperparathyroidism, may commonly be associated with vitamin D deficiencies, and clinical intervention relies on reference data. Vitamin D supplementation may be recommended if animals are deemed to be deficient. Data obtained can be used to improve the care of captive and free-ranging turtles by providing reference ranges, as well as better characterize the health of wild populations.

Translocated and Resident Eastern Box Turtles (Terrapene c. carolina) in New York: Movement Patterns and Habitat Use

Translocation of animals to new habitats is a common conservation management strategy but is of uncertain effectiveness. Terrapene c. carolina (Eastern Box Turtle) are often the subject of translocation efforts. To understand the effectiveness of this strategy, we radio-tracked 19 translocated and 7 resident Eastern Box Turtles to assess movement patterns and habitat use, including hibernacula selection. Using data collected over 4 years from a nature reserve in New York, we compared home range, maximum distance traveled, and total distance traveled for both translocated and resident turtles. We found no difference between translocated or resident turtles or between sexes for any of these measures. These results suggest that translocated turtles at this site adapted well to their new habitat.

MULTI-DRUG RESISTANCE PATTERNS OF ENTERIC BACTERIA IN TWO POPULATIONS OF FREE-RANGING EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA).

Gram-negative isolates (n = 84) from 71% of free-ranging Eastern box turtles (Terrapene carolina carolina) in Illinois and Tennessee, United States, demonstrated resistance to at least one antibiotic while 30% of isolates demonstrated resistance to two or more antibiotics. Resistance was observed against cefoxitin, amoxicillin-clavulanic acid, cefazolin, ampicillin, ticarcillin, cefovecin, and ceftiofur. Gram-positive bacteria were isolated from 49 turtles, and all were observed to be resistant to two or more antibiotics. Gram-positive isolate resistance was observed to penicillin, cefoxitin, oxacillin, clindamycin, amikacin, enrofloxacin, cefovecin, ceftiofur, cefazolin, marbofloxacin, gentamicin, erythromycin, trimethoprim-sulfamethoxazole, and chloramphenicol. Health parameters including packed cell volume, total white blood cell count (WBC), total solids (TS), and weight were not significantly different based on antibiotic resistance patterns; however, decreasing WBC and TS were observed when the number of antibiotic-resistant detections in Gram-positive bacteria increased.

A turtle cognition research demonstration enhances visitor engagement and keeper-animal relationships.

Environmental enrichment techniques present animals with cognitive challenges while providing them opportunities to make choices and exert control over their environment. In this way, cognitive research and training is enriching to animals and can be used as a form of enrichment in zoos and aquariums. Cognitive research demonstrations also provide an opportunity to enhance visitor experience, as well as foster interactions between animals and keepers. We investigated how cognitive research sessions involving eastern box turtles (Terrapene carolina carolina) at Disney's Animal Kingdom® impacted both the rate of visitors coming to the exhibit and the amount of time they spent engaged. Further, we used a questionnaire to assess the impact of keeper participation in these sessions on their relationships with and perceptions of the turtles. While visitation rate to the exhibit was not impacted, cognitive research sessions held visitor attention for longer than keeper interpretation or at times during which no keepers or researchers were present. We also found that keepers that had worked with the turtles for longer and keepers that regularly participated in cognitive research sessions reported stronger bonds with the turtles. Our research suggests that use of cognitive research and training demonstrations for guest viewing in zoos and aquariums may enhance visitor learning opportunities by increasing the amount of time they spend at the exhibit. Our study also provides evidence that participation in such demonstrations by zoo and aquarium professionals can be related to improved keeper-animal bonds, potentially resulting in better husbandry and enhanced animal welfare.

Mass mortality of eastern box turtles with upper respiratory disease following atypical cold weather.

Emerging infectious diseases cause population declines in many ectotherms, with outbreaks frequently punctuated by periods of mass mortality. It remains unclear, however, whether thermoregulation by ectotherms and variation in environmental temperature is associated with mortality risk and disease progression, especially in wild populations. Here, we examined environmental and body temperatures of free-ranging eastern box turtles Terrapene carolina during a mass die-off coincident with upper respiratory disease. We recorded deaths of 17 turtles that showed clinical signs of upper respiratory disease among 76 adult turtles encountered in Berea, Kentucky (USA), in 2014. Of the 17 mortalities, 11 occurred approximately 14 d after mean environmental temperature dropped 2.5 SD below the 3 mo mean. Partial genomic sequencing of the major capsid protein from 1 sick turtle identified a ranavirus isolate similar to frog virus 3. Turtles that lacked clinical signs of disease had significantly higher body temperatures (23°C) than sick turtles (21°C) during the mass mortality, but sick turtles that survived and recovered eventually warmed (measured by temperature loggers). Finally, there was a significant negative effect of daily environmental temperature deviation from the 3 mo mean on survival, suggesting that rapid decreases in environmental temperature were correlated with mortality. Our results point to a potential role for environmental temperature variation and body temperature in disease progression and mortality risk of eastern box turtles affected by upper respiratory disease. Given our findings, it is possible that colder or more variable environmental temperatures and an inability to effectively thermoregulate are associated with poorer disease outcomes in eastern box turtles.

PREVALENCE OF TERRAPENE HERPESVIRUS 1 IN FREE-RANGING EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA) IN TENNESSEE AND ILLINOIS, USA.

Diseases affecting the upper respiratory tract, such as herpesviruses, are well described in captive chelonians worldwide, but their importance in free-ranging populations is less well known. To characterize the disease epidemiology of terrapene herpesvirus 1 (TerHV1), 409 free-ranging eastern box turtles ( Terrapene carolina carolina) in Tennessee and Illinois, US were tested for TerHV1 in 2013 and 2014 using TaqMan quantitative PCR. Whole blood and swabs of the oral mucosa were collected from 365 adults (154 females, 195 males, 16 unknown sex) and 44 juveniles. The prevalence of detection was 31.3% (n=128). Turtles were more likely to be positive for TerHV1 in July (50%; n=67) compared to September (38%; n=44) and May (11%; n=17). Turtles sampled in 2014 had a significantly higher prevalence (50%; n=98) than in 2013 (14%; n=30). In a multivariate model, only season, year, and the interaction between season and year were maintained; turtles were most likely to be positive in July (odds ratio: 30.5) and September (odds ratio: 41.8) 2014 compared to May 2013. The prevalence was not statistically different by state of collection, sex, or age class. Packed cell volume (25.5%) and total solids (4.8 mg/dL) in positive turtles were significantly higher than in negative turtles (23.0%; 4.3 mg/dL). Positive turtles had increased eosinophil concentrations, fewer lymphocytes, and fewer monocytes. No clinical sign was associated with detection of herpesvirus. Widespread DNA evidence of TerHV1 infection was detected in eastern box turtles, and knowledge of the epidemiology of this virus may aid in management of free-ranging and captive individuals.

Spring emergence of Eastern Box Turtles (Terrapene carolina): influences of individual variation and scale of temperature correlates

Many organisms spend considerable time in dormancy to avoid stressful environmental conditions. Understanding the timing and triggers of dormancy behavior is critical for understanding an animal’s life history and behavior. Eastern Box Turtles (Terrapene carolina (L., 1758)) avoid winter temperatures by burrowing into the soil and remaining dormant. Identifying the proximate environmental cues that trigger emergence can improve conservation efforts by reducing potential aboveground turtle mortality. During a 17-year study, half of all variation in emergence timing was attributed to individual variation and the habitat that they occupied during dormancy. We suggest that individual variation in emergence timing is common within populations and confounds efforts to identify reliable emergence cues. Additionally, the scale of meteorological data limits the ability to identify emergence predictors. Using data from temperature loggers placed at dormancy locations, we found that surface air temperatures, averaged over the 5 days prior to emergence, were more strongly related to emergence probability than any variables derived from local weather stations. Turtles generally did not emerge from dormancy until the 5-day mean surface temperatures measured at dormancy sites reached approximately 15 °C. Our results suggest that individuals respond differently to environmental thresholds for emergence and individuals may be characterized as risk-taking or risk-aversive.